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Block copolymers of amino acids. I. Synthesis and structure of copolymers of L ‐alanine or L ‐phenylalanine with D , L ‐lysine‐ d 7 or D , L ‐lysine
Author(s) -
Cardinaux F.,
Howard J. C.,
Taylor G. T.,
Scheraga H. A.
Publication year - 1977
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1977.360160914
Subject(s) - chemistry , copolymer , covalent bond , phenylalanine , polymerization , lysine , amino acid , alanine , polymer chemistry , polymer , stereochemistry , organic chemistry , biochemistry
Water‐soluble block copolymers of the type (A) m ‐(B) n ‐(A) p , where (A) m , p was either poly( D , L ‐lysine‐α,β,β,γ,γ,δ,δ‐ d 7 ) or poly( D , L ‐lysine) and (B) n was either poly( L ‐alanine) or poly( L ‐phenylalanine), were synthesized for conformational studies by proton magnetic resonance spectroscopy. Analytical determination of the amount of the initiator fragment ( n ‐hexylamine) at the C‐terminus of the copolymers was used to obtain the number‐average degrees of polymerization, DP n , and thereby, together with the amino acid composition, to establish the covalent structures of the polymers. The values of DP n were found to be much lower than those deduced from sedimentation equilibrium or form viscosity measurements. These deviations, which also are thought to have arisen in similar studies reported in the literature, are attributable to intermolecular aggregation; the relation of such aggregation to covalent structure (and its effect on the polymerization reaction) is discussed in terms of the conditions and mechanism of synthesis of block copolymers of amino acids.